1. Field of the Invention
The present invention relates to a light-emitting module including a light source and used for a lighting fixture.
2. Description of the Related Art
In recent years, lighting fixtures including a light source with a light-emitting diode element (hereinafter referred to as “LED element”) to emit white light are being broadly and widely adopted. In such a high-output light source for general lighting, because the LED element is a light-emitting body that emits light by application of current, the LED element tends to be heated, and as a result, such a temperature rise of the LED element causes product lifetime to be shortened, hence there is a need to connect the LED element to a metal member such as a metal plate or a heat sink made from aluminum to dissipate heat, and thereby control temperature rise in the LED element.
For example, there is proposed a lighting fixture comprising a light-emitting module and a fixture main body, the light-emitting module being mounted with a plurality of light sources each employing a plurality of LED elements, and the fixture main body being of metal and including a module attaching portion for attaching the light-emitting module by fixing screws (refer to JP 2009-76326 A).
In this lighting fixture, the light sources are joined onto a base substrate of the light-emitting module by a thermosetting fixing material (resin sheet). In addition, the base substrate is fixed to the module attaching portion using the fixing screws or the above-mentioned thermosetting fixing material.
Moreover, proposed in another example is a lighting fixture which has a light-emitting module mounted on a housing thereof, the light-emitting module having a circuit board and a light-distribution controlling lens disposed therein, the circuit board being mounted with LED elements (refer to JP 2010-67415 A).
In this lighting fixture, the circuit board is fixed to a heat-conducting sheet, a heat-conducting plate, and the light-distribution controlling lens by assembly screws, and the light-emitting module is fixed to the housing by fixing screws.
However, the above-described conventional technology leaves the following problems. That is, conventionally, as in the technology described in JP 2009-76326 A, the light sources mounted with the LED elements are fixed to the base substrate which is of metal by an adhesive material such as the thermosetting fixing material; however, the light sources attain a high-temperature state due to heat generation in the LED elements and a thermal expansion differential occurs between the light sources and the base substrate, hence there has been a disadvantage that the adhesive material deteriorates with long-term use resulting in a drop in adhesive strength, heat conductivity and so on, which leads to a lowering of reliability.
As a result, mechanical fixing by screws and the like was required as in the technology described in JP 2010-67415 A, but there has been a problem that, when the substrate mounted with LED elements is screwed onto a metal member like a base plate, electrical insulation properties deteriorate by way of the screws and screw holes, and insulation withstand voltage and so on with external is reduced.